R: Clarification about dsa and ipq806x

[ansuelsmth at gmail.com]

> On Mon, Mar 1, 2021 at 2:26 AM <ansuelsmth at gmail.com> wrote:
> >
> > > Hi
> > >
> > > [Disclaimer: I'm not an OpenWrt developer]
> > >
> > > On 2021-03-01, Ansuel Smith wrote:
> > > [...]
> > > > The idea is to switch this target to dsa but there is a problem...
> > > > Since kernel 5.10 is a testing kernel how should I change the base
> > > [...]
> > > > Do we have some way in openwrt to know if the system use dsa driver or
> > > > swconfig driver?
> > >
> > > I could come up with these strategies:
> > >
> > > - if swconfig is still working in v5.10 with reasonable efforts, the
> > >   easy way out could be to stick with swconfig for the TESTING_KERNEL
> > >   introduction - and switch over to DSA as soon as it is acceptable to
> > >   get rid of kernel v5.4.
> > >
> >
> > That would be the final idea but since 5.10 is a testing kernel it would be
> > very good to test dsa with the other thing...
> 21.02 has been branched. Just convert both of them to DSA.

Just as an info... Master will drop 5.4 and switch to 5.10?

> >
> > > - adding kernel version based conditionals to
> > >   - target/linux/ipq806x/base-files/etc/board.d/02_network
> > >   - target/linux/ipq806x/base-files/etc/board.d/05_compat-version (new)
> > >   - target/linux/ipq806x/image/Makefile (checking for TESTING_KERNEL)
> > >   and toggling DEVICE_COMPAT_VERSION between them as needed. This
> > >   does require (and enforces via DEVICE_COMPAT_VERSION) nuking the
> > >   existing configuration between v5.4 and v5.10 based builds, but would
> > >   allow building either from the same source.
> > >
> >
> > The check if the system has dsa driver is needed only in the 02_network.
> > Still don't know if it's acceptable or not.
> >
> > > - if DSA is mostly working on kernel v5.4 (or could be retrofitted
> > >   *easily*), switching kernel v5.4 in master over to DSA might be
> > >   another option.
> > >   "the dsa driver still lacks vlan support in kernel 5.4" suggests
> > >   that this wouldn't be a reasonable option though.
> > >
> >
> > I never checked since I use a basic network config but software vlan
> > should work. Dsa on 5.4 works good (it's like 2 years that I use it) but
> > still the best approach would be dsa on 5.10 and keep swconfig on 5.4
> >
> > >
> > > Just two questions of my own.
> > >
> > > I think to remember that introducing DSA based drivers is slightly at
> > > odds with devices storing the MAC address in ASCII representation
> > > (uboot-env) rather than binary at a fixed offset, is that an issue
> > > here?
> > > This affects linksys,ea7500-v1, linksys,ea8500 and zyxel,nbg6817
> > >
> >
> > Mac address is set by the gmac driver so we shouldn't have any problem
> > about that.
> >
> > > Is setting tx-fifo-depth still necessary/ useful?
> > > http://lists.infradead.org/pipermail/openwrt-devel/2020-
> > > September/031417.html
> > >
> >
> > Need to check this... In theory this is needed to set mtu to the entire
> > switch. The dsa driver requires to set additional mtu as it has some
> > overhead and by some logs fails to do that. So I still need to investigate
> > about this.
> >
> > >
> > > Regards
> > >       Stefan Lippers-Hollmann
> >
> >
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